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91.
Arraiano LS Kirby J Brown JK 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,116(1):113-122
Septoria tritici blotch, caused by Mycosphaerella graminicola (anamorph Septoria tritici), is one of the most important foliar diseases of wheat in much of the world. Susceptibility of host plants to septoria was
investigated by cytogenetic analysis. A line of Hobbit sib (Dwarf A) in which translocated chromosome 5BS–7BS was nominally
substituted by chromosome arms 5BS and 7BS from Bezostaya 1 had a much lower mean level of septoria than Hobbit sib itself.
By the use of microsatellite markers, it was shown that the 5BS arm of this line had in fact been substituted by the homologous
arm of Chinese Spring. Further investigation of substitution and nullitetrasomic lines demonstrated that chromosome arm 5BS
of Hobbit sib possesses genes, which either promote susceptibility to septoria or suppress resistance. This chromosome arm
has previously been shown to carry genes for resistance to yellow (stripe) rust and powdery mildew, implying a trade-off between
resistances to these two diseases and to septoria in wheat breeding. Bezostaya 1 was found to have specific resistance to
M. graminicola isolate IPO323, probably controlled by the gene Stb6 on chromosome arm 3AS, present in numerous wheat cultivars. It also had partial resistance to septoria distributed over several
chromosomes, which may explain the value of this cultivar as a source of septoria resistance. 相似文献
92.
DellaVecchia MJ Merritt WK Peng Y Kirby TW DeRose EF Mueller GA Van Houten B London RE 《Journal of molecular biology》2007,373(2):282-295
UvrB is a central DNA damage recognition protein involved in bacterial nucleotide excision repair. Structural information has been limited by the apparent disorder of the C-terminal domain 4 in crystal structures of intact UvrB; in solution, the isolated domain 4 is found to form a helix-loop-helix dimer. In order to gain insight into the behavior of UvrB in solution, we have performed NMR studies on [methyl-13C]methionine-labeled UvrB from Bacillus caldotenax (molecular mass=75 kDa). The 13 methyl resonances were assigned on the basis of site-directed mutagenesis and domain deletion. Solvent accessibility was assessed based on the relaxation and chemical shift responses of the probe methyl resonances to the stable nitroxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL). M632, located at the potential dimer interface of domain 4, provides an ideal probe for UvrB dimerization behavior. The M632 resonance of UvrB is very broad, consistent with some degree of monomer-dimer exchange and/or conformational instability of the exposed dimer interface. Upon addition of unlabeled domain 4 peptide, the M632 resonance of UvrB sharpens and shifts to a position consistent with a UvrB-domain 4 heterodimer. A dissociation constant (KD) value of 3.3 microM for the binding constant of UvrB with the domain 4 peptide was derived from surface plasmon resonance studies. Due to the flexibility of the domain 3-4 linker, inferred from limited proteolysis data and from the relaxation behavior of linker residue M607, the position of domain 4 is constrained not by the stiffness of the linking segment but by direct interactions with domains 1-3 in UvrB. In summary, UvrB homodimerization is disfavored, while domain 4 homodimerization and UvrB-domain 4 heterodimerization are allowed. 相似文献
93.
In this study, the product of the CIT3 gene has been identified as a dual specificity mitochondrial citrate and methylcitrate synthase and that of the CIT1 gene as a specific citrate synthase. Recombinant Cit1p had catalytic activity only with acetyl-CoA whereas Cit3p had similar catalytic efficiency with both acetyl-CoA and propionyl-CoA. Deletion of CIT1 dramatically shifted the ratio of these two activities in whole cell extracts towards greater methylcitrate synthase. Deletion of CIT3 had little effect on either citrate or methylcitrate synthase activities. A Deltacit2Deltacit3 strain showed no methylcitrate synthase activity, suggesting that Cit2p, a peroxisomal isoform, may also have methylcitrate synthase activity. Although wild-type strains of Saccharomyces cerevisiae did not grow with propionate as a sole carbon source, deletion of CIT2 allowed growth on propionate, suggesting a toxic production of methylcitrate in the peroxisomes of wild-type cells. The Deltacit2Deltacit3 double mutant did not grow on propionate, providing further evidence for the role of Cit3p in propionate metabolism. (13)C NMR analysis showed the metabolism of 2-(13)C-propionate to acetate, pyruvate, and alanine in wild-type, Deltacit1 and Deltacit2 cells, but not in the Deltacit3 mutant. (13)C NMR and GC-MS analysis of pyruvate metabolism revealed an accumulation of acetate and of isobutanol in the Deltacit3 mutant, suggesting a metabolic alteration possibly resulting from inhibition of the lipoamide acetyltransferase subunit of the pyruvate dehydrogenase complex by propionyl-CoA. In contrast to Deltacit3, pyruvate metabolism in a Deltapda1 (pyruvate dehydrogenase E1 alpha subunit) mutant strain was only shifted towards accumulation of acetate. 相似文献
94.
Hsu JT Hsieh YC Kan WH Chen JG Choudhry MA Schwacha MG Bland KI Chaudry IH 《American journal of physiology. Heart and circulatory physiology》2007,292(6):H2982-H2987
p38 mitogen-activated protein kinase (MAPK) activates a number of heat shock proteins (HSPs), including HSP27 and alpha(B)-crystallin, in response to stress. Activation of HSP27 or alpha(B)-crystallin is known to protect organs/cells by increasing the stability of actin microfilaments. Although our previous studies showed that 17beta-estradiol (E(2)) improves cardiovascular function after trauma-hemorrhage, whether the salutary effects of E(2) under those conditions are mediated via p38 MAPK remains unknown. Male rats (275-325 g body wt) were subjected to soft tissue trauma and hemorrhage (35-40 mmHg mean blood pressure for approximately 90 min) followed by fluid resuscitation. At the onset of resuscitation, rats were injected intravenously with vehicle, E(2) (1 mg/kg body wt), E(2) + the p38 MAPK inhibitor SB-203580 (2 mg/kg body wt), or SB-203580 alone, and various parameters were measured 2 h thereafter. Cardiac functions that were depressed after trauma-hemorrhage were returned to normal levels by E(2) administration, and phosphorylation of cardiac p38 MAPK, HSP27, and alpha(B)-crystallin was increased. The E(2)-mediated improvement of cardiac function and increase in p38 MAPK, HSP27, and alpha(B)-crystallin phosphorylation were abolished with coadministration of SB-203580. These results suggest that the salutary effect of E(2) on cardiac function after trauma-hemorrhage is in part mediated via upregulation of p38 MAPK and subsequent phosphorylation of HSP27 and alpha(B)-crystallin. 相似文献
95.
Heart development in fibronectin-null mice is governed by a genetic modifier on chromosome four 总被引:1,自引:0,他引:1
Absence of the fibronectin (FN) gene leads to early embryonic lethality in both 129S4 and C57BL/6J strains due to severe cardiovascular defects. However, heart development is arrested at different stages in these embryos depending on the genetic background. In the majority of 129S4 FN-null embryos, heart progenitors remain at their anterior bilateral positions and fail to fuse at the midline to form a heart tube. However, on the C57BL/6J genetic background, cardiac development progresses further and results in a centrally positioned and looped heart. To find factor(s) involved in embryonic heart formation and governing the extent of heart development in FN-null embryos in 129S4 and C57BL/6J strains, we performed genetic mapping and haplotype analyses. These analyses lead to identification of a significant linkage to a 1-Mbp interval on chromosome four. Microarray analysis and sequencing identified 21 genes in this region, including five that are differentially expressed between the strains, as potential modifiers. Since none of these genes was previously known to play a role in heart development, one or more of them is likely to be a novel modifier affecting cardiac development. Identification of the modifier would significantly enhance our understanding of the molecular underpinning of heart development and disease. 相似文献
96.
Sarah E. Gergel Yulia Stange Nicholas C. Coops Kasper Johansen Kathryn R. Kirby 《Ecosystems》2007,10(5):688-702
Riparian areas contain structurally diverse habitats that are challenging to monitor routinely and accurately over broad areas.
As the structural variability within riparian areas is often indiscernible using moderate-scale satellite imagery, new mapping
techniques are needed. We used high spatial resolution satellite imagery from the QuickBird satellite to map harvested and
intact forests in coastal British Columbia, Canada. We distinguished forest structural classes used in riparian restoration
planning, each with different restoration costs. To assess the accuracy of high spatial resolution imagery relative to coarser
imagery, we coarsened the pixel resolution of the image, repeated the classifications, and compared results. Accuracy assessments
produced individual class accuracies ranging from 70 to 90% for most classes; whilst accuracies obtained using coarser scale
imagery were lower. We also examined the implications of map error on riparian restoration budgets derived from our classified
maps. To do so, we modified the confusion matrix to create a cost error matrix quantifying costs associated with misclassification.
High spatial resolution satellite imagery can be useful for riparian mapping; however, errors in restoration budgets attributable
to misclassification error can be significant, even when using highly accurate maps. As the spatial resolution of imagery
increases, it will be used more routinely in ecosystem ecology. Thus, our ability to evaluate map accuracy in practical, meaningful
ways must develop further. The cost error matrix is one method that can be adapted for conservation and planning decisions
in many ecosystems. 相似文献
97.
Brian S. Roberts Andrew A. Hardigan Marie K. Kirby Meredith B. Fitz-Gerald C.?Mel Wilcox Robert P. Kimberly Richard M. Myers 《Nucleic acids research》2015,43(21):e145
Highly abundant microRNAs (miRNAs) in small RNA sequencing libraries make it difficult to obtain efficient measurements of more lowly expressed species. We present a new method that allows for the selective blocking of specific, abundant miRNAs during preparation of sequencing libraries. This technique is specific with little off-target effects and has no impact on the reproducibility of the measurement of non-targeted species. In human plasma samples, we demonstrate that blocking of highly abundant hsa-miR-16–5p leads to improved detection of lowly expressed miRNAs and more precise measurement of differential expression overall. Furthermore, we establish the ability to target a second abundant miRNA and to multiplex the blocking of two miRNAs simultaneously. For small RNA sequencing, this technique could fill a similar role as do ribosomal or globin removal technologies in messenger RNA sequencing. 相似文献
98.
Drivers of temporal changes in temperate forest plant diversity vary across spatial scales 下载免费PDF全文
Markus Bernhardt‐Römermann Lander Baeten Dylan Craven Pieter De Frenne Radim Hédl Jonathan Lenoir Didier Bert Jörg Brunet Markéta Chudomelová Guillaume Decocq Hartmut Dierschke Thomas Dirnböck Inken Dörfler Thilo Heinken Martin Hermy Patrick Hommel Bogdan Jaroszewicz Andrzej Keczyński Daniel L. Kelly Keith J. Kirby Martin Kopecký Martin Macek František Máliš Michael Mirtl Fraser J.G. Mitchell Tobias Naaf Miles Newman George Peterken Petr Petřík Wolfgang Schmidt Tibor Standovár Zoltán Tóth Hans Van Calster Gorik Verstraeten Jozef Vladovič Ondřej Vild Monika Wulf Kris Verheyen 《Global Change Biology》2015,21(10):3726-3737
Global biodiversity is affected by numerous environmental drivers. Yet, the extent to which global environmental changes contribute to changes in local diversity is poorly understood. We investigated biodiversity changes in a meta‐analysis of 39 resurvey studies in European temperate forests (3988 vegetation records in total, 17–75 years between the two surveys) by assessing the importance of (i) coarse‐resolution (i.e., among sites) vs. fine‐resolution (i.e., within sites) environmental differences and (ii) changing environmental conditions between surveys. Our results clarify the mechanisms underlying the direction and magnitude of local‐scale biodiversity changes. While not detecting any net local diversity loss, we observed considerable among‐site variation, partly explained by temporal changes in light availability (a local driver) and density of large herbivores (a regional driver). Furthermore, strong evidence was found that presurvey levels of nitrogen deposition determined subsequent diversity changes. We conclude that models forecasting future biodiversity changes should consider coarse‐resolution environmental changes, account for differences in baseline environmental conditions and for local changes in fine‐resolution environmental conditions. 相似文献
99.
Scarf D Miles K Sloan A Goulter N Hegan M Seid-Fatemi A Harper D Colombo M 《PloS one》2011,6(1):e14589
Slot machines are the most common and addictive form of gambling. In the current study, we recorded from single neurons in the 'prefrontal cortex' of pigeons while they played a slot-machine-like task. We identified four categories of neurons that coded for different aspects of our slot-machine-like task. Reward-Proximity neurons showed a linear increase in activity as the opportunity for a reward drew near. I-Won neurons fired only when the fourth stimulus of a winning (four-of-a-kind) combination was displayed. I-Lost neurons changed their firing rate at the presentation of the first nonidentical stimulus, that is, when it was apparent that no reward was forthcoming. Finally, Near-Miss neurons also changed their activity the moment it was recognized that a reward was no longer available, but more importantly, the activity level was related to whether the trial contained one, two, or three identical stimuli prior to the display of the nonidentical stimulus. These findings not only add to recent neurophysiological research employing simulated gambling paradigms, but also add to research addressing the functional correspondence between the avian NCL and primate PFC. 相似文献
100.